: Using the newborn piglet model, hypoglycemia (blood glucose concentration 1 mmol/L for 2 hr) will be induced using an insulin infusion and the glucose clamp technique. Brain tissue will be obtained at various time points between 0 hr and 7 days after exposure to hypoglycemia. The proposed studies will 1) quantitate hypoglycemia-induced free-radical mediated changes in mitochondrial proteins, lipids, and DNA, and demonstrate the mitochondrial specificity of increased free radical production; 2) assess the effect of hypoglycemia on mitochondrial function by measuring mitochondrial calcium uptake and activity of electron transport chain enzymes; 3) establish the role of the antioxidants glutathione and superoxide dismutase and the pro-oxidants nitric oxide and peroxynitrate in mediating hypoglycemia-induced cerebral mitochondrial oxidant injury; and 4) correlate the effects of hypoglycemia-induced alterations in mitochondrial structure and function with neurochemical, immunohistochemical, and morphologic evidence of altered neuronal structure and function with neurochemical, immunohistochemical, and morphologic evidence of altered neuronal structure and cell death.